PFC Controller from STMicroelectronics Integrates Multiple Features for High-End AC-DC Adapters

STMicroelectronics has announced an advanced power factor corrector controller designed to be used in PFC pre-regulators in high-end AC-DC adapters and chargers for laptop PCs and game consoles, in desktop PCs and servers, and in switched-mode power supplies (SMPS) handling up to and more than 250W.

The new L6563 — based on the core of the established and successful L6562 controller — integrates a broad range of additional functions to increase safety and efficiency while minimizing the need for external components.

The L6563 current-mode PFC controller operates in transition mode (TM) and provides a highly cost-effective solution for applications in the region of 100W to 300W, ST officials said. Power in excess of 400W can easily be managed by implementing ST's patented Fixed-Off-Time (FOT) architecture, which increases power capability while maintaining the simplicity and affordability of transition mode operation, they said.

New safety features include brownout and feedback disconnection protection. The former is a non-latched device shutdown function that can be activated when mains undervoltage is detected. The latter prevents uncontrolled output voltage rise, in case of failure of the voltage regulation control loop.

In addition, the integrated circuit provides input voltage feed-forward, tracking-boost operation, inductor saturation detection and leading edge blanking, as well as a direct interface to the cascaded dc-dc converter's pulse-width modulator controller.

Voltage feed-forward can be used to compensate for gain variation with the input voltage, improving the stability of the loop and the transient response to sudden mains voltage changes. Optionally, the chip can be programmed to work with the tracking-boost approach, where the output voltage follows variations in the mains supply voltage. Inductor saturation detection protects against a potentially fatal condition in which its current can reach an abnormally high level.

The PWM controller interface is used to stop the operation of the converter in case of anomalous conditions in the PFC stage, and to turn off the PFC when the converter's load falls below a given threshold, enabling compliance with energy saving recommendations such as Blue Angel, Energy Star, Energy2000 and EU Code of Conduct. The L6563 can be used with ST's new L6668 PWM and L6599 Resonant Controllers, and matches its low power consumption with a start-up current before turn-on of 90µA, and 5mA operating current.

The L6563 is available in an SO14 package. Pricing is $0.28 in quantities of 1,000, or 2,500 for tape-and-reel.